This invention relates generally to the field of sound locating devices and more particularly to a system for detecting and tracking an extremely narrow band of frequencies for a predetermined duration in accordance with specific timing logic.
Convert methods of detecting operating missile sites include the measurement of active radar RF activity when a missile is being launched or the measurement of acoustic energy emitted by the power generator required to run the site before an actual missile launch. The acoustic approach is deemed superior because it provides earlier warning of a potential missile launch, since the radar is used only during the missile flight itself, while the power generator is turned on for long periods of time prior to launch and is a good indicator that the site is occupied. In order to accurately determine the presence of such a site, it is necessary that an extremely narrow band of frequencies peculiar to the specific type of power generator used be selected for detection and tracking. Equally important is the timing logic including means to eliminate system lock-dropouts due to spurious ambient noise. The prior art does not reveal a combination of specific narrow band frequency tracking and particular timing logic in order to positively identify a target.